Tension control apparatus



Feb. 14, 1939. w. E. WHITE TENSION CONTROL APPARATUS Filed July 30, 1936 V 3 Sheets-Sheet 1 Feb. 14, 1939. W.-E. WHITE TENSION CONTROL APPARATUS Filed July so, 1936 I5 Sheets-Sheet 2 /NVWTOR W E. WHITE 8y LU ATTOR/Vf) Feb. 14, 1939. w. E. WHITE 2,146,869

TENS ION CONTROL APPARATUS Filed July 30, 1956 3 Sheets-Sheet 3 /0/ m3 FIG. 7

Patented Feb. 14, 1939 UNITED STATES PATENT OFFICE TENSION CONTROL APPARATUS Walter E. White, Montreal, Quebec, Canada, assignor to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Application July 30, 1936, Serial No. 93,389

7 Claims. (01. 242-45) This invention relates to a tension control 341- instance. wh n th tension in the strand I3 inparatus, and more particularly to a control appacreases, the pulley Will be w Shifting ratus for a reeling motor to maintain the tension the Condenser p a 22 t the left, as e ed in constant on the material being reeled. 4. to decrease the c pac ty o the c e s An object of the invention is to provide an efand when the tension n the t d decreases. fective and efiicient mechanism for controlling pulley I6 W be moved up y y the Spring the tension on material being advanced. 25, moving condenser pl t 2 o t r h as In accordance with one embodiment of the v w d i t n r as the capa i y f the invention, the capacity of a condenser is varied Condenser- The p at s f condenser 0 are so 1 in accordance with the tension on a strand to pe hat the p y of the condense! 10 contr l the speed of a reeling ot r, changes in proportion to the relative movement Other objects and advantages will appear from of the pl e This condenser forms one arm of the following description taken in conjunction an impedance bridge having preferably W ed with the following dra i in whi h condensers 29 in complementary arms, and a s Fig. 1 is a diagrammatic view of a tension con- Variable Condenser 3 in the fourth trol apparatus embodying the invention; T impedanc brid e is energiz d t r h a Fig. 2 is a, front elevation of a, portion of the transformer 32 which is in a plate circuit Of an apparatus including a. diagrammatic view of a oscillator tube 33. This tube is provided with a tensi n indicator; grid bias 34 and by-pass condenser 35, and the Fig 3 is a, ide l vati of th apparatus h w circuit in which it is connected is made regenerain Fi 2; tive by a coil 3b in its grid circuit, coupled to Fig. 4 is a detail view of the condenser taken ts energizing transformer 37, and be d a on line 4-4 of Fig. 3; part of both the grid and plate circuits whereby Fig. 5 is a sectional view taken on line 5-4.5 energy in the plate circuit is fed back into the I of Fig. 4; grid circuit, thus causing oscillations to be main- Fig. 6 is a diagrammatic view of an alternative tained. The coil 36 is connected in parallel type of control motor to be used with the control with a tuning condenser 38 for selecting the fresystem of Fig. 1, and quency of the output of tube 33. The plate cur- Fig. l is a diagrammatic view of a modified rent for the oscillator tube 33 is provided by a form of control system. rectifier tube 4i and a filter circuit 42 connected The invention is illustrated in Fig. 1 in conto the output of the rectifier tube. The output nection with a tape-up reel ll, driven by a direct of the impedance bridge is conn t through current motor 12,120 reel a strand 13, after passan impedance matching transformer 43 to an ing through the idler rollers I 4 from any suitamplifier circuit comprising a tube dd preferable source 15, which may represent a wire drawably of the tetrode type. This tube is provided ing apparatus, wire coating apparatus, or other with a grid bias id and by-pass condenser 46, source of wire to be wound upon the reel. The the grid bias being so chosen that the tube has idler pulleys M are arranged to form in efiect a a rectilinear plate current relative to its grid triangle with a pulley 16, Figs. 1 and 2, which is voltage. Tube 44 is energized thro h a ransmounted on a support I! slidably mounted on former 47 which supplies a rectifier tube 48 from a vertical bar IS. A cord I 9 is attached to the Which'the rectified current passes through-a upper end of support I! and passes over an idler filter circuit 49 to a resistance 5! to which the pulley H to be attached to a slidable plate 22 plate and screen grid of the tube are connected. of a condenser 20. The other end of this plate While the plate current of tube 44 is preferably has a cord 23 secured thereto which passes over rectilinear with respect to its grid voltage, it will an idler pulley 24 and is connected to a spring be evident that a non-rectilinear characteristic 25 which tends to continuously urge the plate may be used, in which case the movable con- 22 .toward the right as viewed in Fig. 4. The denser plate 22 should be of such configuration slldable plate 22 of the condenser is associated that a given variation in tension will cause a r with a fixed plate 26 mounted in an insulating corresponding variation in the plate circuit of 50 support 21. The plates 22 and 26 are insulated tube 44. from each other by a suitable dielectric material The coil of a. relay 52 is connected into the 28 oi. mica, or the like. The capacity of this plate circuit of tube 44, and when the tension condenser is varied by the relative movement of the strand is at the selected value, there is of the condenser plat s 2 and 2 Thus, for Just suflicient current passing through the coil 52 to hold its armature in its mid-position. It now the tension in the strand decreases, the current in the plate circuit of tube 44 will decrease and allow the armature of relay 52 to engage its back contact 53. This closes a circuit through a relay 54 from the full wave rectifier 55 preferably of the copper oxide type energized from the transformer 56. The armature of relay 54 is weighted so as to increase the time delay thereof. The closing of the contact of relay 54 closes a circuit through the coil of a slow to operate relay 5'I. Relay 51 is made slow to operate so that it will not close upon a momentary change in tension of the strand. The closing of the contact of relay 5'I closes a circuit through the field coil 58 of a motor 59. The motor 59 adjusts the variable resistance 6| which is in the field coil 62 of reeling motor l2. This motor is also provided with a field coil 63, which supplies the normal excitation for the motor. This excitation may be varied manually by means of a rheostat 64 to change the tension on the strand according to the size of the strand being reeled. The field coil 62, therefore, supplies only the control excitation for the reeling motor I2. When the field coil 58 of motor 59 is energized in response to a decrease in tension, motor 59 rotates in such a direction as to increase the amount of resistance 6| in series with the field coil 62 so as to decrease the excitation and increase the speed of this motor to compensate for the decrease in tension. When the tension on the strand becomes too large, the plate current of tube 44 will increase to such an extent that relay 52 will close on its front contact 65 and energize relay 66, also having a weighted armature. The closure of relay 66 will energize slow to operate relay 61 and when the contacts of relay 6'! close, field coil 68 of motor 59 will be energized. This causes the motor 59 to rotate in such a direction as to decrease the amount of resistance 6| in series with the field coil 62 of motor I2, thereby increasing the field excitation of motor I2 to decrease its speed and thereby reduce its tension. Since the compensation for tension variations depends entirely upon the tension, it'will be seen that the apparatus will maintain the tension constant regardless of whether the source of supply of the strand I5 delivers the strand at a constant speed or not. w

The apparatus is also provided with means for maintaining the tension on the strand constant during periods of acceleration and deceleration as during starting or stopping. When the switch 'II is first closed to set the apparatus in motion, the double throw switch I2 is also closed on one of its sets of contacts. This causes the energization of the field coil 13 of a motor I4 through a manually adjustable resistance I5. It will be seen that the current for the armature excitation of motor I2 passes through a variable resistance I6 .which is controlled by motor I4. Since it is desired to accelerate the motor I2 at a definite rate, the resistance I6 should be at a maximum when the motor I2 is started. The closing of switch I2 then causes motor I4 to rotate in such a direction as to gradually decrease the amount of resistance I6 in series with-the armature of motor I2, so that when the motor I2 reaches normal operating speed, the minimum resistance I6 is in circuit with its armature, at which time the switch I2 is opened. In order to decelerate the motor I2 the double throw switch I2 is closed on its oppositecontacts so as to gradually increase the amount of resistance I6 in the arma- .normal operating speed ture circuit of motor l2. The amount of resistance 16 in the armature circuit of motor I2, when it is desired to stop the reeling operation, may thus be increased until it attains a value a such that the motor I2'will gradually slow down and come to a stop, whereupon the D. C. supply may be disconnected in any well-known manner. When it is desired to restart the reeling operation, the D. C. source may be reconnected and the switch I2 reversed, thereby to gradually decrease the amount of resistance I6 in the armature circuit of motor I2 to permit sufiicient current to fiow in the armature circuit, to start the motor I2 and gradually increase its speed to the where a minimum amount of resistance I6 will be included in the armature circuit of motor I2, whereupon the switch I2 may be moved to its inoperative mid position until it is again desired to stop the reeling operation.

In order to inform the operator of the amount of tension applied to a strand by the apparatus, the support I1 is provided with an upwardly extending arm 11 which carries a brush I8 engaging a commutator I9. Each conducting segment of the commutator is connected to one of a plurality of graduated resistances 8|. A meter 82 is connected through a resistance 83 to a common lead 84 connected to one of the commutator segments, and the other side of the meter is connected through a battery 85 to the brush I8. Since the position of the brush I8 depends upon the amount of tension in the strand, it will be seen that one of the resistances 8| or the resistance 83 will be in series with the meter, and since each of these resistances has a difierent value preferably graduated with respect to the other resistances, the position of brush III or the tension in the strand will be indicated by the meter 82. A second meter 86 and a variable resistance 81 may be associated with the battery 85 to adjust the potential at the output terminals of the battery 85. I

The operation of this embodiment of the invention is as follows: The strand I3, from the source I5, having been strung around the idler switches II and I2 the source of direct current will have been connected to the D. C. leads. In its previous operation, the switch I2 would have been moved to position to increase the resistance in resistance I6 to the point where the motor I2 had stopped. Therefore, when the switch II is closed and the switch I2 closed on its contacts, which will drive the motor I4 in a clockwise direction (Fig. 1), the amount of resistance in resistance 16 will be gradually reduced to a minimum, whereupon the motor I2 will gradually accelerate to the desired speed, asdetermined by the setting of the resistance 64. If the strand I3 being reeled encounters only the proper amount of resistance, the control circuit for motor 59 will remain inactive. However, if the tension in the strand increases beyond a predetermined point, relay 52 will be energized to attract its armature, thereby energizing relays 66 and 61 to connect the field coil 68 of motor 59 to the D. C. lines, thereby decreasing the resistance in resistance 6| and decreasing the speed of motor I2 to slow down the reeling operation. If there is a decrease in tension in the strand I3, the condenser 28 will afiect its circuit to cause relay 52 to move its armature into engagement with contact 53, whereupon relays 54 and 51 will be energized to connect the field coil 58 of motor 59 to the D. C. lines, thereby to increase the strength of resistance 6| and increase the speed of motor I2. The condenser 20 and its associated circuit will thus control the tension in the wire until it is desired to stop the reeling operation, whereupon switch 12 may be closed on its contacts, which will cause the field coil 13 of motor 14 to be energized to drive the motor 14in a direction to gradually increase the resistance in resistance 16 to the point where the motor I2 will stop, whereupon the switch 12 may be moved to its open position, switch 1I opened, and the D. C. source disconnected, whereupon the just described operations may be repeated, to cause the apparatus to perform a new reeling operation.

The apparatus thus far described is illustrated in connection with a direct current reeling motor.

Fig. 6 illustrates the use of an alternating current motor I8I for this purpose. The apparatus enclosed in broken lines in Fig. 6 may be substituted directly for the apparatus enclosed in broken lines in Fig. l. The stator of motor I8I is shown connected directly across the alternating current line I82. The armature of motor I8I is of the wound type and has a manually adjustable resistance I83 and an automatically adjustable resistance I84 in series therewith. The manually adjustable resistance I83 is adjusted to obtain the desired normal tension of the strand depending upon its size, while the resistance I84 is adjusted by means of a motor I85. Field coils I86 and I81 of motor I are energized by the apparatus disclosed in Fig. l in the same manner that field coils 58 and 68 of motor 59 are energized in that system, and the speed of motor I8I will, therefore, be controlled in accordance with the tension on the strand.

Fig. 7 illustrates a modified form of the invention in which a take-up reel I 0i is driven by a direct current motor I02 to reel a strand I03 from a supply source I04. A pair of idler rollers I05 form in effect a triangle with a roller I06 which is urged in a downward direction by the weight IIO. Intermediate the weight and pulley I06 a pair of brushes I 08 and I01 are moved by the weight. The brush I08 is associated with an indicator system I09 which is identical with the indicator system described in connection with Fig. 1 and the description of the indicator circuit will, therefore, not be repeated. The brush I01 forms part of the control circuit and is movable along a pair of conducting segments III and H2 which are separated by an insulating section I I 3. If the tension attains too high a value, brush I01 will be moved into engagement with the conducting segment I I I and when the tension becomes too low, it will 'move into engagement with a conducting segment II2. For automatic tension control a switch I I4 is closed. If now the tension is too high, brush I01 will engage the conducting segments I I I, and a circuit may be traced from one side II5 of a direct current source of energy through a commutator I I6 which is rotated by a motor II1 through a speed reducer so that the commutator will rotate at approximately one revolution per minute. The purpose of the commutator H6 is to prevent hunting of the system, a brush II8 engages the commutator, and from here the circuit passes through brush I 01, segment III, the switch II4 through the back contacts of a relay IIO through the coil of relay I2I,

limit switch I22 to the other side I23 of the direct current source. This causes relay I 2I to make on its front contact, thereby closing a circuit through the field coil I24 of motor I 25. It will be seen that the armature of the reeling motor I02 is connected directly across the direct current source while its field coil I26 is connected to the direct current source through a variable resistance I21. This variable resistance is controlled by the motor I25. The tension being too high when the brush I01 engages the segment III, motor I25 will be rotated in such a direction as to decrease the portion of resistance I21 in the field coil I26 so as to increase the field energization of motor I02 and decrease its speed. If now the tension decreases to such an extent that the brush I01 engages the conducting segment II2, the coil of relay H8 will be energized through the back contacts of relay I2I. The circuit through the coil of relay II9 passes through limit switch I20. The energization of coil II9 will cause the field coil I28 of motor I25 to be energized rotating the arm of the variable resistance I21 in such a direction as to increase the portion of this resistance in series with the field coil I26 of motor I02, thereby decreasing the field energization of motor I02, and increasing its speed. A fixed resistance I29 may be connected across the armature of motor I25 to decrease its speed. It will be seen that limit switches I20 and I22 are actuated by the moving arm of rheostat I21 and prevent the motor I25 from rotating this arm beyond the limits of the rheostat.

If it is desired to manually control the tension in accordance with the indications of the tension indicating system I09, the switch II 4 is opened and a pair of manual switches I3I and I32 may be used. Thus, by closing switch I3I, relay H9 is energized closing its contacts to energize field coil I28, whereby the resistance I21 will be adjusted to increase the tension, whereas if the switch I32 is closed relay I2I will be energized, closing its contacts to energize field coil I24 whereby the resistance I 21 will be adjusted to decrease the tension in the strand.

It is not the intention to limit the arrangement of the bridge to an adjustable condenser since an adjustable inductance or resistance may be substituted for the condenser 20 shown. In this case the fixed condenser in the opposite arm is replaced by a matched inductance or resistance.

The term strand as used in the specification and appended claims is intended to embrace sheet or strip material as well as other elongated forms of material capable of being advanced by reels, rollers, or other advancing means.

' While the invention has been described in connection with certain specific embodiments thereof, it will be understood that many changes and modifications may be made therein without departing from the spirit and scope of the invention.

What is claimed is:

1. In a strand handling apparatus, motive means for applying a tension to a strand, a variable condenser, means for varying said condenser in accordance with the tension on said strand, and control means including a bridge circuit responsive to the adjustment of said condenser which forms an arm of said bridge circuit for controlling the tension applied to the strand by said motive means.

2. In a strand handling apparatus, motive means for applying a tension to a strand, an impedance bridge including a condenser having relatively movable plates, the shape of the plates being such that the output current of the bridge is linear in relation to the movement of the plates, means for moving said condenser plates in response to variations in tension, and means for controlling said motive means in response to the output of said bridge.

3. Inastrandhandllng apparatus, motive means for tensioning a strand, an impedance bridge including a condenser having relatively movable plates, means for moving said plates in response to tension variations, an amplifier circuit including a thermionic tube for amplifying the output of said bridge, said tube and the shape of the condenser plates being so correlated as to' provide a linear output of said tube relative to the movement of the condenser plates, and means for controlling said motive means in response to the output of said tube.

4. In a strand handling apparatus, motive means for applying a tension to the strand, a condenser variable in response to said tension, an impedance bridge including said condenser in one arm thereof, an oscillator for supplying current to said bridge, and means for controlling said motive means in accordance with the-output of said bridge.

5. 'In a strand handling apparatus, a reeling motor, a field coil for supplying the normal excitation for the motor, a manually controlled rheostat for varyingthe excitation of said field coil to select the normal excitation of the motor, a second field coil for supplying a control excitation to said motor, a second rheostat for controlling the excitation of the second field coil, a reversible motor for operating said second rheostat, a bridge circuit responsive to tension in the strand being handled, means responsive to the output of said bridge for controlling the operation of said reversible motor, and a circuit operable simultaneously with the operation of said reversible motor for effecting an auxiliary control over said reeling motor to cause acceleration or deceleration of said reeling motor.

6. In a strand handling apparatus, a reeling motor, a field coil for supplying the normal excitation for the motor, a manually controlled rheostat for varying the excitation of said field coil to select the normal excitation of the motor, a second field coil for supplying a control excitation to said motor, a second rheostat for controlling the excitation of the second field coil, a reversible motor for operating said second rheostat, a bridge circuit responsive to tension in the strand being handled, means responsive to the output of said bridge for controlling the operation of said reversible motor, and a circuitoperable simultaneously with the operation of said reversible motor for efiecting an auxiliary control over said reeling motor to cause acceleration or deceleration. of said reeling motor, including a motor driven rheostat in series with the armature of said reeling motor.

7. In a strand handling apparatus, a reeling motor, a field coil for supplying the normal excitation for the motor, a manually controlled rheostat for varying the excitation of said field coil to select the normal excitation of the motor, a second field coil for supplying a control excitation to said motor, a second rheostat for controlling the excitation of the second field coil, a reversible motor for operating said second rheostat, a bridge circuit responsive to tension in the strand being handled, means responsive to the output of said bridge for controlling the operation of said reversible motor, a' circuit operable simultaneously with the operation of said reversible motor for effecting an auxiliary control over said reeling motor to cause acceleration or deceleration of said reeling motor, including a motor driven rheostat in series with the armature of said reeling motor, and a switch for controlling the operation of said last mentioned rheostat.

WALTER E. WHITE. 

